Young people have suffered less under the COVID-19 virus than older people medically, but experts say the gap has narrowed, and so-called superspreading among the young is a factor.

“The epidemic is changing. People in their 20s, 30s and 40s are increasingly driving its spread,” said Dr. Takeshi Kasai, World Health Organization regional director for the Western Pacific, in a virtual press conference Aug. 18.

“Many are unaware they’re infected — with very mild symptoms or none at all. This can result in them unknowingly passing on the virus to others,” he added.

But on Sept. 28, a 19-year-old college student died, apparently of neurological complications related to the coronavirus.

Chad Dorrill, a sophomore at Appalachian State University in Boone, North Carolina, was diagnosed with COVID-19 in early September and suffered from later complications.

Dorrill developed additional complications even after being cleared by his doctor to return to Boone from his home county, according to an announcement from Appalachian State University Chancellor Sheri Everts.

“All of us must remain vigilant with our safety behaviors wherever we are in our community. We must flatten the curve, but to do so, we must persevere,” Everts said.

Research published Sept. 23 from the Centers for Disease Control and Prevention (CDC) in Atlanta reports that the COVID-19 incidence was highest in adults ages 20 to 29 years during June to August 2020 in the United States.

The report states that “younger adults likely contribute to community transmission of COVID-19,” and that increases in positive test results among adults ages 20 to 39 preceded increases among those 60 and older by an average of 8.7 days across the southern United States in June 2020.

As of Oct. 5, the 18-to-29 age group led all positive cases in the United States with 23.7%, or 1,269,397 cases, according to CDC data. The 50-to-64 age group followed in second with 20.6% of positive cases, or 1,000,476 cases.

Research shows that the coronavirus carries long-term health implications, even in younger adults.

A multistate telephone survey of adults who had symptoms and tested positive for COVID-19 showed 35% had not returned to their usual state of health when interviewed two to three weeks after testing, according to a report by the CDC.

Twenty percent of 18-to-34-year-olds with no chronic medical conditions reported they had not returned to their usual state of health.

A study published this month in the Journal of the American Heart Association found that pediatric patients 18 and younger with acute or prior coronavirus infection can have a broad range of cardiac findings, even though they are experiencing mild symptoms.

While data show that cases were the highest among older adults in the early stages of the pandemic, German epidemiologist Karl Lauterbach suggested in April, when the pandemic was widespread in China and Italy, that thousands of young people may have helped seed the COVID-19 pandemic since last December.

“Experience maybe believes that it’s a severe disease for older people,” Lauterbach told VOA in March. “But we now know that many of the younger people also get severely ill and may sustain long-term consequences.”

“They get a very severe and atypical pneumonia and may end up in the [intensive care unit],” Lauterbach, a scientist and member of Germany’s Bundestag Parliament, said. “And they have way more severe disease than we initially believed.”

In December 2019, as COVID-19 was emerging in China, colleges and universities worldwide released hundreds of thousands of students home for winter break. Many of the more than 360,000 Chinese students who study in the U.S. returned to China for the holiday.

A month later, they and other international students returned to their campuses in the U.S. and around the world as COVID-19 was gaining speed.

In March, U.S. colleges and universities began their spring breaks, times when students traditionally head to warm beach destinations, such as in Florida, Texas and Mexico, to blow off steam after studying for midterms.

Dr. Sean O’Leary, associate professor of pediatrics-infectious diseases at the University of Colorado Anschutz Medical Campus, told VOA that in response to the wave of COVID-19 cases in the U.S., many universities shut down their campuses, sent students home or asked them to return from spring break to clean out their rooms, and then put them on airplanes for points around the country.

“From the perspective of the U.S. as a country, was that the best choice?” O’Leary asked. Campuses were “one place where we knew there was widespread transmission.”

Lauterbach said the disease is insidious in younger people because they typically show only mild or no symptoms, and scientists now believe that 80% of COVID-19 transmission occurs among those who don’t seem ill.

A study by the American Academy of Pediatrics looked at more than 2,000 youths ages 18 and younger in China.

Doctors from Shanghai Children’s Medical Center and Shanghai Jiao Tong University School of Medicine wrote that where the virus first emerged, in Hubei province, 13% of confirmed cases had asymptomatic infection, a rate that “almost certainly understates the true rate of asymptomatic infection, since many asymptomatic children are unlikely to be tested.”

Research published Aug. 6 by JAMA Internal Medicine found that many COVID-19 patients remained asymptomatic for a prolonged period, and the viral load was similar to that of symptomatic patients.

Older children have also been shown to transmit the coronavirus as much as adults, according to a large study from South Korea.

The study, which analyzed nearly 65,000 people in South Korea, found that children younger than 10 were around half as likely to spread the virus as adults. However, young people ages 10 to 19 years old are more likely than other age groups to disperse COVID-19 into households.

Of 10,592 household contacts, 11.8% had COVID-19, with 18.6% being index patients ages 10 to 19. It was 1.9% for the 48,481 non-household contacts.

“We should make it clear to younger people that if they behave in a careless fashion, that they are not only putting themselves, their peers, older people and peers [with underlying conditions] at risk,” Lauterbach said, “but they put themselves at risk and their best friends. So, we need to convey a message that this is a serious disease for all age groups.”

“It is quite clear that not many young people die from the disease,” Lauterbach said.

“But it is astonishing that we see very, let's say, remarkable numbers of younger people in the ICU and also often on ventilator support,” he said.

“Currently, we do not know whether they will fully recover their lung function or not. We definitely do not know that for certain. So, we have to take this way more seriously than we did in the past.”

Kathleen Struck contributed to this report.